U.S. patent application number 11/878355 was filed with the patent office on 2008-03-13 for piston cartridge.
Invention is credited to Donald E. Blackman, James M. Heim, Michael Landrum, Douglas Miller.
Application Number | 20080060513 11/878355 |
Document ID | / |
Family ID | 39168255 |
Filed Date | 2008-03-13 |
United States Patent
Application |
20080060513 |
Kind Code |
A1 |
Miller; Douglas ; et
al. |
March 13, 2008 |
Piston cartridge
Abstract
A piston cartridge having a piston chamber, an inlet port, an
outlet port, and a piston moveable between a first position and a
second position. Also, the cartridge includes a first barrier
positioned between the piston and the inlet port and a first
sealing member moveable between the first barrier and the inlet
port, wherein the first sealing member seals the inlet port when
positioned adjacent to the inlet port but allows the fluid into the
chamber when positioned adjacent to the first barrier. In addition,
the cartridge also includes a second barrier positioned adjacent to
the outlet port and a second sealing member moveable between the
piston and the second barrier, wherein the second sealing member
seals the outlet port when positioned adjacent thereto but allows
the fluid to pass through the outlet port when positioned adjacent
to the second barrier.
Inventors: |
Miller; Douglas; (New
Berlin, WI) ; Landrum; Michael; (Rockford, IL)
; Blackman; Donald E.; (Tinley Park, IL) ; Heim;
James M.; (Rockford, IL) |
Correspondence
Address: |
BAKER & HOSTETLER LLP
WASHINGTON SQUARE, SUITE 1100, 1050 CONNECTICUT AVE. N.W.
WASHINGTON
DC
20036-5304
US
|
Family ID: |
39168255 |
Appl. No.: |
11/878355 |
Filed: |
July 24, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60843701 |
Sep 12, 2006 |
|
|
|
Current U.S.
Class: |
92/172 |
Current CPC
Class: |
F04B 53/162 20130101;
F04B 1/0538 20130101; F04B 53/22 20130101; F04B 53/16 20130101;
F04B 1/0421 20130101; F04B 53/1002 20130101; Y10T 137/7839
20150401; Y10T 137/7845 20150401; F04B 1/053 20130101; F04B 53/109
20130101; F04B 1/0408 20130101 |
Class at
Publication: |
92/172 |
International
Class: |
F16J 1/00 20060101
F16J001/00 |
Claims
1. A piston cartridge, comprising: a piston chamber; an inlet port
positioned adjacent to the piston chamber and providing a pathway
through which a fluid may enter the piston chamber; a first outlet
port positioned adjacent to the piston chamber and providing a
pathway though which the fluid may exit the piston chamber; a
piston at least partially positioned within the piston chamber and
moveable between a first position that is relatively close to the
inlet port and a second position that is relatively far from the
inlet port; a first barrier positioned between the piston and the
inlet port; a first sealing member positioned and moveable between
the first barrier and the inlet port, wherein the first sealing
member substantially seals the inlet port when positioned adjacent
to the inlet port but allows the fluid into the piston chamber when
positioned adjacent to the first barrier; a second barrier
positioned adjacent to the first outlet port; and a second sealing
member positioned and moveable between the piston and the second
barrier, wherein the second sealing member substantially seals the
first outlet port when positioned adjacent thereto but allows the
fluid to pass through the first outlet port when positioned
adjacent to the second barrier.
2. The piston cartridge of claim 1, wherein the first sealing
member includes a substantially spherical portion.
3. The piston cartridge of claim 1, wherein the second barrier is
positioned outside of the piston chamber.
4. The piston cartridge of claim 1, further comprising: a housing
that includes the piston chamber; and a threaded portion on the
housing that is configured to allow for the piston cartridge to be
screwed onto a pump.
5. The piston cartridge of claim 4, further comprising: a groove
external to the housing that accommodates the second barrier
therein.
6. The piston cartridge of claim 4, further comprising: a groove
external to the housing configured to guide the fluid flowing
therein to a desired location.
7. The piston cartridge of claim 4, wherein the second barrier
comprises a C-shaped spring positioned external to the housing.
8. The piston cartridge of claim 1, further comprising: a second
outlet port positioned adjacent to the piston chamber and providing
another pathway though which the fluid may exit the piston chamber;
and a third sealing member positioned and moveable between the
piston and the second barrier, wherein the third sealing member
substantially seals the second outlet port when positioned adjacent
thereto but allows the fluid to pass through the second outlet port
when positioned adjacent to the second barrier.
9. The piston cartridge of claim 1, further comprising a spring
that applies a restorative force to the piston when the piston is
at a location other than the second position.
10. A method of operating a piston, the method comprising: moving
the piston within a piston chamber from a first position that is
relatively close to an inlet port of the piston chamber to a second
position that is relatively far from the inlet port; allowing a
fluid to flow into the piston chamber upon moving the piston from
the first position to the second position by allowing a first
sealing member configured to seal the inlet port when positioned
adjacent thereto to move away from the inlet port; and preventing
the fluid from flowing out of the piston chamber upon moving the
piston from the first position to the second position by allowing a
second sealing member to move toward an outlet port and thereby
form a seal therewith.
11. The method of claim 10, further comprising: moving the piston
from the second position to the first position; preventing the
fluid from flowing into the piston chamber upon moving the piston
from the second position to the first position by biasing the first
sealing member toward the inlet port; and allowing the fluid to
flow out of the piston chamber upon moving the piston from the
second position to the first position by biasing the second sealing
member away from the outlet port.
12. The method of claim 10, further comprising: preventing the
first sealing member from entering the piston chamber using a first
barrier positioned between the inlet port and the piston
chamber.
13. The method of claim 10, further comprising: preventing the
second sealing member from detaching from the piston chamber using
a second barrier positioned between outside of the outlet port.
14. The method of claim 10, further comprising: removing the piston
from a pump that the piston is operating in by unscrewing the
piston and thereby releasing threaded portions on an exterior
portion of a housing that includes the piston chamber.
15. The method of claim 10, further comprising: allowing the fluid
to flow out of the piston chamber upon moving the piston from the
second position to the first position by biasing a third sealing
member away from a second outlet port connected to the piston
chamber.
16. The method of claim 10, further comprising: preventing the
fluid from flowing out of the piston chamber upon moving the piston
from the first position to the second position by allowing a third
sealing member to move toward a second outlet port connected to the
piston chamber and to thereby form a seal therewith.
17. A piston cartridge, comprising: fluid accommodating means for
accommodating a fluid; fluid inletting means for inletting the
fluid into the fluid accommodating means, wherein the fluid
inletting means is positioned adjacent to the fluid accommodating
means and provides a pathway through which the fluid may enter the
fluid accommodating means; fluid outletting means for outletting
the fluid from the fluid accommodating means, wherein the fluid
outletting means is positioned adjacent to the fluid accommodating
means and providing a pathway though which the fluid may exit the
fluid accommodating means; fluid moving means for moving the fluid,
wherein the fluid moving means is at least partially positioned
within the fluid accommodating means and moveable between a first
position that is relatively close to the fluid inletting means and
a second position that is relatively far from the fluid inletting
means; first barrier means for providing a first barrier, the first
barrier means positioned between the fluid moving means and the
fluid inletting means; first sealing means for providing a first
fluid seal, the first sealing means positioned and moveable between
the first barrier means and the fluid inletting means, wherein the
first sealing means substantially seals the fluid inletting means
when positioned adjacent to the fluid inletting means but allows
the fluid into the fluid accommodating means when positioned
adjacent to the first barrier means; second barrier means for
providing a second barrier, the second barrier means positioned
adjacent to the fluid outletting means; and second sealing means
positioned and moveable between the fluid moving means and the
second barrier means, wherein the second sealing means
substantially seals the fluid outletting means when positioned
adjacent thereto but allows the fluid to pass through the fluid
outletting means when positioned adjacent to the second barrier
means.
18. The piston cartridge of claim 17, further comprising: biasing
means for biasing the fluid moving means toward the second
position, wherein the biasing means is positioned adjacent to the
fluid moving means.
19. The piston cartridge of claim 17, further comprising: guiding
means for guiding fluid flowing out of the fluid outletting means
to a desired location that is external to the fluid accommodating
means.
20. The piston cartridge of claim 17, further comprising:
restricting means for restricting motion of the second barrier
means, wherein the restricting means is positioned adjacent to at
least two sides of the second barrier means.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. Provisional Patent
Application No. 60/843,701 titled, PRESSURE COMPENSATED PUMP, filed
Sep. 12, 2006, which is hereby incorporated herein by reference in
its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to fluid pumps. More
particularly, the present invention relates to pumps capable of
maintaining a constant horsepower output even as the pressure at
which they operate fluctuates.
BACKGROUND OF THE INVENTION
[0003] Pumps that are capable of maintaining a constant horsepower
output, even as the pressure at which they operate fluctuates, are
currently available. These pumps are designed to use a given amount
of horsepower inputted into them, generally through a motor, and to
maximize the amount of horsepower that they output, regardless of
the pressure at which they operate. Thus, such pumps operate more
efficiently than other pumps that are not capable of maintaining a
constant horsepower output.
[0004] Typically, pumps that are capable of maintaining a constant
horsepower output are operable in relatively low pressure ranges.
On the other hand, pumps that are operable in higher pressure
ranges are unable to maintain a constant horsepower output as the
operating pressure of the pump changes. Typically, such higher
pressure pumps are multi-stage pumps and are essentially made up of
multiple pumps that are linked together using a mechanism for
switching between the multiple pumps.
[0005] Accordingly, it would be desirable to provide novel pumps
and methods that are capable of maintaining a constant horsepower
output even at high pressures. It would also be desirable to
provide novel pumps that consist of infinite stages (i.e., that are
truly single pumps).
[0006] In addition to the above, it would also be desirable to
provide pumps that are modular and therefore easily, and
cost-effectively repairable. Further, it would be desirable to
provide pumps that maximize efficiency by minimizing the total
volume of the piston chambers included therein.
SUMMARY OF THE INVENTION
[0007] The foregoing needs are met, to a great extent, by the
present invention, wherein in one embodiment thereof, a piston
cartridge is provided. The piston cartridge includes a piston
chamber. The piston cartridge also includes an inlet port
positioned adjacent to the piston chamber and providing a pathway
through which a fluid may enter the piston chamber. The piston
cartridge further includes a first outlet port positioned adjacent
to the piston chamber and providing a pathway though which the
fluid may exit the piston chamber. In addition, the piston
cartridge also includes a piston at least partially positioned
within the piston chamber and moveable between a first position
that is relatively close to the inlet port and a second position
that is relatively far from the inlet port. Also, the piston
cartridge includes a first barrier positioned between the piston
and the inlet port. Further, the piston cartridge includes a first
sealing member positioned and moveable between the first barrier
and the inlet port, wherein the first sealing member substantially
seals the inlet port when positioned adjacent to the inlet port but
allows the fluid into the piston chamber when positioned adjacent
to the first barrier. In addition, the piston cartridge also
includes a second barrier positioned adjacent to the first outlet
port. The piston cartridge also includes a second sealing member
positioned and moveable between the piston and the second barrier,
wherein the second sealing member substantially seals the first
outlet port when positioned adjacent thereto but allows the fluid
to pass through the first outlet port when positioned adjacent to
the second barrier.
[0008] According to another embodiment of the present invention, a
method of operating a piston is provided. The method includes
moving a piston within a piston chamber from a first position that
is relatively close to an inlet port of the piston chamber to a
second position that is relatively far from the inlet port. The
method also includes allowing a fluid to flow into the piston
chamber upon moving the piston from the first position to the
second position by allowing a first sealing member configured to
seal the inlet port when positioned adjacent thereto to move away
from the inlet port. The method further includes preventing the
fluid from flowing out of the piston chamber upon moving the piston
from the first position to the second position by allowing a second
sealing member to move toward an outlet port and thereby form a
seal therewith.
[0009] According to yet another embodiment of the present
invention, another piston cartridge is provided. The piston
cartridge includes fluid accommodating means for accommodating a
fluid and fluid inletting means for inletting the fluid into the
fluid accommodating means, wherein the fluid inletting means is
positioned adjacent to the fluid accommodating means and provides a
pathway through which the fluid may enter the fluid accommodating
means. The piston cartridge also includes fluid outletting means
for outletting the fluid from the fluid accommodating means,
wherein the fluid outletting means is positioned adjacent to the
fluid accommodating means and providing a pathway though which the
fluid may exit the fluid accommodating means and fluid moving means
for moving the fluid, wherein the fluid moving means is at least
partially positioned within the fluid accommodating means and
moveable between a first position that is relatively close to the
fluid inletting means and a second position that is relatively far
from the fluid inletting means. In addition, the piston cartridge
also includes first barrier means for providing a first barrier,
the first barrier means positioned between the fluid moving means
and the fluid inletting means and first sealing means for providing
a first fluid seal, the first sealing means positioned and moveable
between the first barrier means and the fluid inletting means,
wherein the first sealing means substantially seals the fluid
inletting means when positioned adjacent to the fluid inletting
means but allows the fluid into the fluid accommodating means when
positioned adjacent to the first barrier means. The piston
cartridge also includes second barrier means for providing a second
barrier, the second barrier means positioned adjacent to the fluid
outletting means and second sealing means positioned and moveable
between the fluid moving means and the second barrier means,
wherein the second sealing means substantially seals the fluid
outletting means when positioned adjacent thereto but allows the
fluid to pass through the fluid outletting means when positioned
adjacent to the second barrier means.
[0010] According to still another embodiment of the present
invention, another method of operating a pump is provided. The
method includes rotating an eccentrically shaped cam about a first
axis. The method also includes translating the cam along the first
axis. The method further includes maintaining a position along the
first axis of a bearing that is adjacent to the cam as the cam
translates along the first axis. In addition, the method also
includes pushing a piston positioned adjacent to the bearing with
the bearing as the cam rotates. The method further includes
maintaining a substantially constant power output level from the
pump as the cam translates along the first axis.
[0011] There has thus been outlined, rather broadly, certain
embodiments of the invention in order that the detailed description
thereof herein may be better understood, and in order that the
present contribution to the art may be better appreciated. There
are, of course, additional embodiments of the invention that will
be described below and which will form the subject matter of the
claims appended hereto.
[0012] In this respect, before explaining at least one embodiment
of the invention in detail, it is to be understood that the
invention is not limited in its application to the details of
construction and to the arrangements of the components set forth in
the following description or illustrated in the drawings. The
invention is capable of embodiments in addition to those described
and of being practiced and carried out in various ways. Also, it is
to be understood that the phraseology and terminology employed
herein, as well as the abstract, are for the purpose of description
and should not be regarded as limiting.
[0013] As such, those skilled in the art will appreciate that the
conception upon which this disclosure is based may readily be
utilized as a basis for the designing of other structures, methods
and systems for carrying out the several purposes of the present
invention. It is important, therefore, that the claims be regarded
as including such equivalent constructions insofar as they do not
depart from the spirit and scope of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 illustrates a cross-section of a pump according to a
first embodiment of the present invention.
[0015] FIG. 2 illustrates a perspective view of a cross-section of
an interior portion of the pump illustrated in FIG. 1.
[0016] FIG. 3 illustrates a portion of the cross-section of the
pump illustrated in FIG. 1 wherein the cam shaft is in a fully
stroked position.
[0017] FIG. 4 illustrates a portion of the cross-section of the
pump illustrated in FIG. 1 wherein the cam shaft is in a fully
destroked position.
[0018] FIG. 5 illustrates three representative horsepower curves
for the pump illustrated in FIGS. 1-4.
[0019] FIG. 6 illustrates a cross-section of a piston cartridge
according to yet another embodiment of the present invention.
[0020] FIG. 7 is a peripheral view of the piston cartridge
illustrated in FIG. 6.
[0021] FIG. 8 illustrates a semi-transparent perspective view of
the pump ring sub-assembly illustrated in FIG. 2 that includes
three cartridges and one lube cartridge.
[0022] FIG. 9 illustrates another semi-transparent perspective view
of the pump ring sub-assembly illustrated in FIG. 8.
[0023] FIG. 10 illustrates a perspective view of a representative
implementation of the pump illustrated in FIG. 1.
DETAILED DESCRIPTION
[0024] The invention will now be described with reference to the
drawing figures, in which like reference numerals refer to like
parts throughout. FIG. 1 illustrates a cross-section of a pump 10
according to a first embodiment of the present invention. As
illustrated in FIG. 1, the pump 10 has a radial design (as opposed
to an axial design) and includes a motor 12 that is connected to a
pump shaft 14. The pump shaft 14 houses a spring assembly 16 having
a first end that is adjacent to the motor 12 and a second end that
is adjacent to a cam 17.
[0025] According to certain embodiments of the present invention,
the spring assembly 16 includes a stack of two, three, or more
springs. When three springs are use, a heavy spring (i.e., a spring
with a high spring constant and capable of exerting a large spring
force when compressed) is typically positioned furthest to the
right in the spring assembly 16 illustrated in FIG. 1. Then, a
medium spring is positioned in the middle of the spring assembly 16
and a light spring is positioned next to the cam 17. Together, the
three springs form the progressive spring assembly 16 that, as will
be explained below, will be used to position the cam 17 relative to
other components in the pump 10. According to certain embodiments
of the present invention, each spring in the plurality of springs
in the spring assembly 16 has a different spring rates/force.
However, configurations where two or more springs have the same
spring rate/force are also within the scope of the present
invention.
[0026] In FIG. 1, the spring assembly 16 is positioned about an
internal spring guide 13. The internal spring guide 13 is
concentrically located inside the shaft 14, abuts the pin 11, and
maintains the spring assembly 16 substantially in the center of the
shaft 14. Positioned at the end of the spring assembly 16 closest
to the cam 17 is a cam seal plug 15 designed to prevent liquid that
is lubricating the cam 17 from leaking onto the spring assembly
16.
[0027] In operation, the motor 12 is mechanically connected to the
pump shaft 14 and cam 17 and causes both to rotate. According to
certain embodiments of the present invention, the cam 17 is rotated
at between about 3,000 and about 4,000 rpm. However, other rpm
ranges are also within the scope of the present invention.
[0028] As illustrated in FIG. 1, the pump shaft 14 is supported by
a pair of shaft bearings 18. A shaft seal assembly 20 is positioned
around the pump shaft 14 and near the end that is adjacent to the
motor 12. Also positioned around the pump shaft 14 is a pair of
saddles 24 that are generally used to keep other components of the
pump 10 in position, as will become apparent pursuant to reviewing
the accompanying figures.
[0029] Positioned adjacent to the end of the cam 17 that is located
opposite the spring assembly 16 is a pilot piston 22 that
effectively acts as an actuator for moving the cam 17 along a
longitudinal axis, A, of the pump shaft 14. According to certain
embodiments of the present invention, a substantially spherical
object (e.g., a ball) or a thrust bearing assembly such as element
23 in FIG. 1 is positioned between the pilot piston 22 and the cam
17 to facilitate the axial spinning of the cam 17 relative to the
pilot piston 22. The substantially spherical object or thrust
bearing assembly 23 is typically capable of spinning as the cam 17
rotates.
[0030] According to certain other embodiments of the present
invention, the pilot piston 22 is a small rod that extends along
the longitudinal axis, A, of the pump shaft 14 and comes to a point
that is positioned against the cam 17. According to such
embodiments, the pilot piston 22 provides a single-point contact
against the cam 17 and there is, therefore, no associated torque
arm. As such, the cam 17 may spin at a relatively high rpm and a
rotary seal is not necessary. The same is true of embodiments of
the present invention where the single-point contact is replaced
with the thrust bearing assembly 23 or substantially spherical
object.
[0031] The cam 17 has a plurality of grooves 26 formed therein and,
as illustrated in FIG. 1, is resultantly indented and is typically
eccentric about the cam's longitudinal axis, A (which is also the
longitudinal axis of the pump shaft 14 in FIG. 1). Received in each
of the grooves 26 illustrated in FIG. 1 is a sphere 28A, 28B, 28C,
28D. Each of the spheres 28A, 28B, 28C, 28D illustrated in FIG. 1
is positioned between a piston 30 and a lube piston 31 and in the
same plane as the central axes of the pistons 30, 31. Typically,
the lube piston 31 allows a lubricant to be introduced into the
interior of the pump shaft 14 and the piston 30 is configured to
act as a fluid displacement mechanism (discussed below). According
to certain embodiments of the present invention, in operation, the
eccentrically-shaped cam 17, the spheres 28A, 28B, 28C, 28D, and
the pump shaft 14 are all rotated about the longitudinal axis, A,
of the pump shaft 14 by the motor 12 in bearing rings 44 and 45
illustrated in FIG. 2, which in combination act as an
eccentric.
[0032] In FIG. 1, spheres 28A and 28B are vertically aligned with
each other and make up a first pairs of spheres while spheres 28C
and 28D also are vertically aligned with each other and make up a
second pair of spheres. Each sphere pair is also aligned vertically
with one of the pistons 30 and one of the lube pistons 31
illustrated in FIG. 1. In each pair of spheres, one sphere (e.g.,
28A and 28D) is positioned relatively close to the longitudinal
axis, A, of the pump shaft 14 while the other sphere in the pair of
spheres (e.g., 28B and 28C) is positioned relatively far from the
same axis. Upon rotation of the cam 17 and spheres 28A, 28B, 28C,
28D, saddles 24, and bearing rings 44 and 45 about the longitudinal
axis, A, which creates an eccentric, each of the spheres 28A, 28B,
28C, 28D will affect the displacement position of the eccentric
which will come into contact with the pistons 30 and lube pistons
31.
[0033] Upon contact of the eccentric with one of the pistons 30 and
lube pistons 31, the spheres 28B, 28C that are relatively far from
the longitudinal axis, A, of the pump shaft 14 will push the
eccentric and one of the pistons 30 or lube pistons 31 outward and
the spheres 28A, 28D that are relatively near the longitudinal
axis, A, will allow the other piston 30 and lube piston 31 to
travel back inward towards the longitudinal axis, A. The total
distance that the pistons 30 travel upon one complete rotation of
the eccentric and cam 17 (i.e., the piston stroke) determines how
much fluid is capable of flowing through the pump 10. Generally,
the greater the distance that the piston 30 travels, the more fluid
will flow through the pump 10.
[0034] The pump 10 illustrated in FIG. 1 also includes a tank 32
(i.e., an oil reservoir), a suction filter 34, a return tube 36, an
input oil groove 38 from the tank 32, and a pump output port 40
that accommodates the flow of high-pressure oil from the pump 10.
In operation, oil flows from the tank 32, through the suction
filter 34, through the input oil groove 38, and into piston
chambers (e.g., pumping chamber 62 illustrated in FIG. 6) that are
adjacent to the pistons 30 illustrated in FIG. 1. The pistons 30
then apply pressure to the oil in the piston chambers and the oil
is released through the pump output port 40. However, other pump
configurations are also within the scope of the present
invention.
[0035] FIG. 2 illustrates a perspective view of a cross-section of
an interior portion of the pump 10 illustrated in FIG. 1. The
cross-section illustrated in FIG. 2 is perpendicular to the
cross-section illustrated in FIG. 1. The front face of FIG. 2 also
coincides with the cross-section of a pump ring sub-assembly 25. As
illustrated in FIG. 2, the two spheres 28A, 28B on either side of
the cam 17 are positioned adjacent to the saddle 24 and a bearing
ring 42. The outside of the bearing ring 42 is adjacent to one of
the two eccentrics 44, 45 illustrated in FIG. 2. A forward
eccentric 44 is illustrated as being positioned at the proximate
end of the cross-section and a rear eccentric 45 is positioned
behind the forward eccentric 44 (i.e., closer to the motor 12).
[0036] As will be discussed below, the pump 10 is a pressure
compensated pump that, upon appropriate positioning of the cam 17
relative to the pump shaft 14 and pistons 30, is capable of
delivering variable fluid flow as a function of and at any pressure
at which the pump 10 is operated. According to certain embodiments
of the present invention, and as will also be discussed below, the
pump 10 is configured to optimize its own output performance by
monitoring the pressure at which it is operating and by using that
pressure value to control its own operation.
[0037] By definition, in order to determine the horsepower of a
pump, the fluid flow (e.g., gallons/minute) out of the pump is
first multiplied by the pressure at which the pump is operating and
that calculated value is then divided by a constant. When using,
for example, a 1.5 horsepower motor as the motor 12 to drive the
pump 10, it is typically preferable to operate the pump 10 at as
close to the rated horsepower level to optimize performance. It is
also typically preferable to be able to maintain the approximate
rated horsepower level of operation of the pump, even when the
pump's operating pressure fluctuates.
[0038] Currently, there is a market demand for pumps that are
capable of maintaining a constant horsepower output of up to the
10,000 psi range and beyond, even as the pressure at which they
operate fluctuates (i.e., there is a need for pressure compensation
pumps that operate at relatively high pressures). However,
currently available pressure compensation pumps, at best, only
operate in ranges up to between 2,000 and 5,000 psi. Also, even at
these relatively low pressures, currently available pressure
compensation pumps are complex, expensive, and cumbersome
mechanisms.
[0039] Currently available pumps that do operate in the 10,000+psi
range are multi-stage pumps and, therefore, do not provide
continuous pressure compensation. Rather, these multi-stage pumps
experience a step down in output power every time the rising
operating pressure of the pump forces a switch or transition to a
new stage. In other words, these pumps are relatively inefficient
compared to pressure compensation pumps. In addition, the step-down
mechanisms used in such pumps include either complex, expensive,
and cumbersome moving swash plates and/or valving plates or
unloading valves for each stage.
[0040] According to certain embodiments of the present invention,
the pump 10 is an infinitely variable single-stage pressure
compensation pump (i.e., with infinite stages) that can operate
anywhere from approximately 1 psi to approximately 10,000 psi and
beyond. As has been illustrated in FIGS. 1 and 2, the components of
the pump 10 are designed to be relatively simple and, as will be
discussed below, operation of the pump 10 is relatively
efficient.
[0041] FIG. 3 illustrates a portion of the cross-section of the
pump 10 illustrated in FIG. 1 wherein the cam shaft 17 is in a
fully stroked position (i.e., in a position where the spheres 28B
and 28C that are closest to the pistons 30 sit in the shallowest
portions of the grooves 26). FIG. 4 illustrates a portion of the
cross-section of the pump 10 illustrated in FIG. 1 wherein the cam
shaft 17 is in a fully destroked position (i.e., in a position
where the spheres 28B, 28C that are closest to the pistons 30 sit
in the deepest portions of the grooves 26). FIG. 4 also illustrates
a pilot pressure port 46 that is connected to high pressure
passages of the pump 10. According to certain embodiments of the
present invention, this pressure is used to control the position of
the pilot piston 22.
[0042] As will be appreciated by one of skill in the art upon
practicing certain embodiments of the present invention, when the
cam 17 is positioned as illustrated in FIG. 3 and is rotated by the
motor 12 (illustrated in FIG. 1), the pistons 30 experience the
maximum degree of travel allowable by the pump 10 and provide the
most flow to maintain a given horsepower. On the other hand, when
the cam 17 is positioned as illustrated in FIG. 4, the pistons 30
experience the minimum degree of travel that still allows the pump
10 to operate as intended. Adjustment of the position of the cam
17, discussed below, will allow the pump 10 to provide the desired
maximum horsepower at the operating pressure of the pump 10.
[0043] FIG. 5 illustrates three representative horsepower curves.
The solid curve is based on theoretical horsepower data while the
two dashed curves are based on measured data of two typical
two-stage pumps that do not follow the horsepower curve. According
to certain embodiments of the present invention, the profile of the
cam 17 (i.e., the curvature of the grooves 26), along with the
design of the spring assembly 16 (i.e., the relative forces exerted
by the springs included in the spring assembly 16 upon compression)
and the relationship of the pilot piston force, keep the pump 10
operating along the theoretical horsepower curves illustrated in
FIG. 5. As noted above, although theoretical values may be used,
the shape of the horsepower curve is typically determined via
empirical studies. The formula that defines a horsepower curve is
an exponential function and is generated using hundreds of data
points taken at different operating pressures and flow volumes of
the pump 10 that maximize the horsepower output of the pump 10.
[0044] According to certain embodiments of the present invention,
the horsepower curve is smoothed so as to be continuous. This
allows for the grooves 26 in the cam 17 to also be smooth and
continuous. When the pump 10 is in operation, the pilot piston 22
exerts a force upon the cam 17 that is typically either equal to or
a function of the pressure at which the pump 10 itself is
operating. According to certain embodiments of the present
invention, a closed feedback loop signal is used to control the
pilot piston 22 (discussed below). According to other embodiments
of the present invention, a manual or automated interface could be
provided to control the pilot piston 22. Also, other means of
controlling the pilot piston 22 that will become apparent to one of
skill in the art upon practicing the present invention are also
within the scope of the present invention.
[0045] Regardless of how it is controlled, the force exerted,
either directly or indirectly, onto the cam 17 by the pilot piston
22 positions the cam 17 at a location relative to the pistons 30
that is substantially optimal for the operating pressure of the
pump 10. In other words, the cam 17 is positioned so that the
spheres 28A, 28B, 28C, 28D cause the pistons 30 to travel distances
that provide a flow rate for the pump 10 that substantially
optimizes the rated horsepower of the pump 10 at that operating
pressure.
[0046] Returning to the discussion of FIGS. 3 and 4, in the fully
stroked position illustrated in FIG. 3, the pump 10 delivers a
relatively high flow rate at a relatively low pressure (e.g., only
a few psi). In the fully destroked position illustrated in FIG. 4,
the pump delivers a relatively low flow at a relatively high
pressure (e.g., between 6,000 and 10,000 psi or more). According to
certain embodiments of the present invention, the pilot piston 22
may be used to position the cam 17 at any location between the
fully strocked and fully destrocked positions. As such, all flow
rates and associated pressures that substantially maximize the
horsepower of the pump 10 are available. In other words, the pump
10 is an infinitely positionable pressure compensated pump that
operates with the movement of very few components.
[0047] According to certain embodiments of the present invention,
each piston 30 that is positioned about the forward eccentric 44
illustrated in FIG. 2 has a corresponding sister piston 30 that is
positioned about the rear eccentric 45 about the longitudinal axis,
A, of the pump shaft 14. However, other shapes are also possible
and are contemplated within the present invention. For example,
according to an embodiment of the present invention where five
pistons 30 are included, the five pistons may make a star or
pentagon shape (i.e., the pistons may be offset by 72 degrees from
each other).
[0048] According to certain embodiments of the present invention,
the resultant vector of the set of pistons in each eccentric 44, 45
is 180.degree. out-of-phase with the resultant vector of the set of
pistons in the other eccentric 44, 45. This feature keeps the
eccentrics 44, 45 illustrated in FIG. 2 from torquing the cam 17
and therefore at least substantially eliminates the need to provide
counter-balances in the pump 10. In turn, this method of operation
reduces the overall cost and complexity of the pump 10.
[0049] Although only two eccentrics 44, 45 are illustrated in FIG.
2, according to other embodiments of the present invention, three
or more eccentrics may be used. When, for example, three eccentrics
are included in the pump 10, each piston has two sister pistons
that are operating in phase with the piston 30 and each sister
piston is offset by 120 degrees about the longitudinal axis, A, of
the pump shaft 14. Similarly, when, for example, four eccentrics
are included, each piston 30 has three in-phase sister pistons.
Thus, according to certain embodiments of the present invention,
the forces exerted on the cam 17 by a first piston are
substantially always balanced by forces exerted on the cam 17 by
one or more offset, in-phase, sister pistons.
[0050] According to other embodiments of the present invention,
methods of operating a pump are provided. According to some of
these embodiments, a pump (e.g., the above-discussed pump 10) is
operated at a first pressure level (e.g., approximately 1,000 psi).
The same pump is also operated at a first power output level that,
for example, may be selected to at least substantially coincide
with the power level of a motor that drives the pump (e.g.,
approximately 1.5 horsepower according to certain embodiments of
the present invention).
[0051] Then, the first pressure level at which the pump is operated
at is transitioned to a second pressure level. This second pressure
level, according to certain embodiments of the present invention,
is above approximately 6,000 psi or is above approximately 10,000
psi in other embodiments or even higher according to other
embodiments.
[0052] During transitioning of the operating pressure level of the
pump from the first pressure level to the second pressure level (or
even to other levels), certain embodiments of the present invention
substantially maintain the first power output level. One exemplary
way to implement maintaining the first power output level includes
allowing the pilot piston 22 to move along the longitudinal axis,
A, as the pump pressure increases and decreases. According to such
embodiments, the cam 17 is displaced to various locations along the
longitudinal axis, A, by the pilot piston 22.
[0053] As discussed above, according to certain embodiments of the
present invention, the spring assembly 16 and the pilot piston 22
are specifically designed to move the spheres 28A, 28B, 28C, 28D in
the grooves 26 of the cam 17 illustrated in FIG. 1 as the operating
pressure of the pump 10 changes. More specifically, the spheres
28A, 28B, 28C, 28D are moved in the grooves 26 such that, as the
spheres 28A, 28B, 28C, 28D spin about the longitudinal axis, A, the
pistons 30 will be displaced distances that will maintain the rated
power output level of the pump 10. As such, the above-discussed
substantially maintaining the first power output level of the pump
may be implemented using the components illustrated in FIG. 1.
[0054] The above-discussed method also may include minimizing
vibrations in the pump by providing counterbalanced fluid
displacement mechanisms. According to certain embodiments of the
present invention, this step may be implemented by offsetting the
positions of the pistons 30 in the pump 10 as illustrated in FIG. 2
and by operating the pistons 30 out of phase with each other to
offset each piston's force on the cam 17.
[0055] FIG. 6 illustrates a cross-section of a piston cartridge 60
according to yet another embodiment of the present invention. The
piston cartridge 60 includes one of the above-discussed pistons 30
in a pumping chamber 62. At the top and bottom of the cross-section
of the cartridge 60 illustrated in FIG. 6 are oil input ports 64.
Also illustrated in FIG. 6 and positioned to the right of the input
ports 64 is an inlet check ball 66 and a check ball guide 68. At
the sides of the pumping chamber 62 are oil output ports 76 that
have output check balls 74 positioned adjacent thereto. The
cartridge 60 also includes buttress threads 48 on the outside
thereof and a piston return spring 50 that extends between the
piston 30 and one end of the piston cartridge 60.
[0056] The piston cartridge 60 illustrated in FIG. 6 is a
self-contained pumping element that may be used not only in
conjunction with the pump 10 illustrated in FIG. 1 but also in
conjunction with other pumps and devices. The types of other pumps
and devices in which the piston cartridge 60 may be used will
become apparent to one of skill in the art upon practicing one or
more embodiments of the present invention.
[0057] As illustrated in FIG. 6, the piston 30 is positioned in the
center of the piston cartridge 60. More specifically, the piston 30
is in the pumping chamber 62 and functions as a pumping piston that
pumps oil in the pump 10. As discussed above, the piston 30 moves
as it contacts one or more of the eccentrics illustrated in FIGS.
1-4. However, a conventional (i.e., fixed displacement) cam shaft
or other element may also be used to move the piston 30.
[0058] As the piston 30 illustrated in FIG. 6 moves to the right,
the suction check ball 66 is drawn toward the piston 30 by the
suction created by the motion of the piston 30. The piston 30 also
draws oil through the input ports 64, around the suction check ball
66, and into the pumping chamber 62. When oil is drawn into the
pumping chamber 62 as discussed above, the output check balls 74
illustrated in FIG. 6 prevent oil from flowing through output ports
76 because the output check balls 74 are drawn inward by the piston
suction and held in place by a C-spring 78 (illustrated in FIG. 7)
biased towards the seats.
[0059] Immediately to the right of the check ball 66 is the check
ball guide 68, which receives the check ball 66 and may be made of
any material but which is often made of a plastic. The ball guide
68 includes a plurality of lobes 70 (i.e., protrusions) that guide
the check ball 66 centrally relative to the check ball guide 68.
The ball guide 68 also includes a plurality of grooves 72 that
allow oil to pass from the input ports 64 and into the pumping
chamber 62.
[0060] As illustrated in FIG. 6, also included in the piston
cartridge 60 is a spring 73 that is positioned between the check
ball 66 and the check ball guide 68. This spring 73 biases the
check ball 66 toward the input ports 64, and when the piston 30 is
not creating suction pressure, the check ball 66 is positioned
against the input ports 64 and prevents oil from flowing
therethrough.
[0061] When the piston 30 moves to the left in FIG. 6, the input
ports 64 are at least substantially sealed off by the suction check
ball 66. Also, the output check balls 74 are pushed away from the
piston 30 and oil is pushed through the output ports 76 located on
the sides of the pumping chamber 62.
[0062] FIG. 7 is a peripheral view of the piston cartridge 60
illustrated in FIG. 6. As illustrated in FIG. 7, a low-pressure oil
input groove 92 directs fluid to the input ports 64. Also, a
C-spring 78 wraps around a high pressure oil output groove 80 on
the outside of the piston cartridge 60 and extends over the output
ports 76. As such, the C-spring 78 prevents the output check balls
74 from moving away from the cartridge 60 entirely while the piston
30 is moving to the right in FIG. 6. It should also be note that,
according to certain embodiments of the present invention, a tab or
other protrusion 57 is located on an inner surface of the C-spring
78. This protrusion 57 is typically inserted into a retaining notch
59 formed in the high-pressure oil output groove 80 and prevents
the C-spring 78 from rotating about the cartridge 60.
[0063] Also illustrated in FIG. 7 is a threaded region 82 that
typically includes threads (e.g., the buttress threads 48
illustrated in FIG. 6) that allow for the cartridge 60 to be
screwed into a pump or other device and to thereby fix the location
of the cartridge 60. Of course, other coupling methods can also be
used (e.g., a coupling assembly). The earlier-discussed piston
return spring 50 is illustrated in FIG. 7 and pushes against the
piston 30. This spring 50 restores the piston 30 to a location to
the right-hand-side of FIG. 7 when not counter-acted by other
forces. In addition, a pair of high-pressure O-ring seals 86 and an
individual low-pressure O-ring 88 are illustrated in FIG. 7. The
pair of O-ring seals 86 are designed to prevent oil leakage of the
cartridge 60.
[0064] FIG. 8 illustrates a semi-transparent perspective view of
the pump ring sub-assembly 25 illustrated in FIG. 2 that includes
three cartridges 60 such as the one illustrated in FIG. 7 and one
lube cartridge 61 that houses the above-discussed lube piston 31.
The ring sub-assemble 25 also illustrates bolt holes 63 that allow
for the insertion of bolts through the ring sub-assembly 25 in
order to attach the ring sub-assembly 25 to other components of the
above-discussed pump 10.
[0065] When oil is pumped out of the cartridge 60, the oil flows
into the a high-pressure oil output groove 80. Also, it should be
noted that there are low-pressure input oil passage 96 illustrated
in FIG. 8 that allow oil to travel from the tank 32 (see FIG. 1) to
the input grooves 92 of the cartridges.
[0066] FIG. 9 illustrates another semi-transparent perspective view
of the pump ring sub-assembly 25 illustrated in FIG. 8. After
flowing into the high-pressure oil output groove 80 illustrated in
FIG. 8, the oil typically flows through one of the output hole
passages 94 illustrated in FIG. 8 and out toward the pump output
port 40 (see FIG. 9) of the pump 10. The flow of this oil is
typically through one of the channels 81 illustrated in FIG. 9.
FIG. 10 illustrates a perspective view of a representative
implementation of the pump 10 illustrated in FIG. 1.
[0067] One advantage of certain embodiments of the present
invention is that the geometry discussed above minimizes the amount
of dead volume in the pumping chamber 62 when the pistons 30 are
fully stroked. In other words, the size of the pumping chamber 62
is minimized and, because oil is somewhat compressible, the fact
that there is less oil present to compress maximizes the efficiency
of the pump 10. Keeping the two output ports 40 small and close to
the end stroke of the piston 30 minimizes the dead volume.
[0068] Yet another advantage of certain embodiments of the present
invention has to do with the fact that the threaded nature of the
cartridge 60 makes the cartridge 60 conveniently and completely
removable from the pump 10. Since the check ball guide 68 may be
designed to be easily removable from the cartridge 60 (e.g., by
merely unsnapping one or more tabs), the guide 68 may also
cost-effectively be repaired or replaced by another without having
to interrupt the use of the pump for any extended length of
time.
[0069] According to other embodiments of the present invention, a
method of operating a piston such as, for example, piston cartridge
60, is provided. The method includes introducing a hydraulic fluid
(e.g., oil) into a piston chamber (e.g., pumping chamber 62). The
method also includes applying a force to the hydraulic fluid in the
chamber using a piston. This step may be implemented, for example,
by moving piston 30 in FIG. 6 to the left, thereby applying
pressure to the oil in the pumping chamber 62.
[0070] In addition to the above, the method also may include
releasing the hydraulic fluid from a plurality of outlet ports
(e.g., ports 76), wherein at least one of the outlet ports remains
substantially unblocked by the piston while the piston is applying
force to the hydraulic fluid. In other words, when implementing
this step using the cartridge 60, during operation, the stroke of
the piston 30 does not totally block the output ports 76.
[0071] The method, according to certain embodiments of the present
invention, also includes substantially sealing an outlet port in
the plurality of outlet ports using a moveable obstruction (e.g.,
output check balls 74) upon the piston being moved away from the
outlet port. The method may also include substantially surrounding
the piston chamber using a retainer (e.g., C-spring 78). Then, the
method may include using the retainer to prevent the moveable
obstruction from completely detaching from the piston cartridge. In
other words, the C-spring 78 may be used to keep the output check
balls 74 from moving away from the cartridge upon the piston 30
moving to the left in FIG. 6.
[0072] The method may also include including a housing (illustrated
as item 98 in FIG. 6) as part of the piston chamber. The method may
also include providing a threaded portion (e.g., threaded portion
82) on the housing, thereby facilitating the housing being removed
from the pump. In other words, because of the threads, the housing
98 of the cartridge 60 may be unscrewed and replaced with a new
cartridge 60.
[0073] The above-discussed pump 10 and cartridges 60 may be
implemented in a number of ways. For example, FIG. 9 illustrates a
perspective view of a representative implementation of the pump 10
discussed above. FIG. 10 then illustrates another perspective view
of the piston cartridge 60 illustrated in FIGS. 6 and 7. Finally,
FIG. 11 illustrates another semi-transparent perspective view of
the pump ring sub-assembly 25 illustrated in FIG. 8.
[0074] In addition to the above, the method may also include
allowing the hydraulic fluid to enter the chamber through an inlet
port (e.g., ports 64) and substantially sealing the inlet port upon
the piston being moved toward the inlet port. Typically, this may
be done using the suction check ball 66. Further, the method may
include partially restricting motion of the moveable obstruction
that substantially seals the inlet using protrusions. This step may
be implemented using the check ball guide 68 and the lobes thereon
70. Lastly, the method may include allowing the hydraulic fluid to
flow through channels in the moveable obstruction that
substantially seals the inlet. This step may be implemented using
the above-discussed grooves 80.
[0075] The many features and advantages of the invention are
apparent from the detailed specification, and thus, it is intended
by the appended claims to cover all such features and advantages of
the invention which fall within the true spirit and scope of the
invention. Further, since numerous modifications and variations
will readily occur to those skilled in the art, it is not desired
to limit the invention to the exact construction and operation
illustrated and described, and accordingly, all suitable
modifications and equivalents may be resorted to, falling within
the scope of the invention.
* * * * *